It has been noted as being desirable or necessary in a number of apparatus and processes to sense the rate of change of changing rotational speeds of a rotational element. One example of such a need is found in connection with the use of brakes for slowing a rotating member such as an automotive vehicle wheel. As has been pointed out, sensing the rate of change of changing rotational speeds of a braked rotating member such as an automotive vehicle wheel can be used in conjunction with appropriate arrangements for optimizing braking effects. A variety of approaches to sensing rate of change of changing rotational speeds and/or vehicle wheel slip has been proposed heretofore, as the interested reader will discover from prior patents, references cited therein, and references cited during the prosecution of the applications which resulted in those cited patents. Interested readers are referred to such prior patents for a more complete discussion of a range of types of sensors.
It will be understood that the sensitivity or responsiveness of sensors responsive to wheel slip and/or rates of change of changing rotational speeds of a rotatable element and/or rates of retardation is an important element in determining the performance of any system proposing to obtain control of braking and driving processes. While a competent designer knowledgeable in the arts pertinent to the sensors referred to is able to design and have made and place into use sensors effective to accomplish control by signalling occurences of excessive rates of retardation, it has been heretofore recognized as difficult to accomplish all of substantial sensitivity or responsiveness of a sensor, and ruggedness in use, and optimization of response to varying brake operating conditions. Inevitably, the skilled designer must compromise among the desired goals, with the compromises made favoring certain desired characteristics over other characteristics which are desired but perhaps unattainable.
It has been recognized heretofore that optimal sensitivity or responsiveness of a sensor may be facilitated by rendering the sensor responsive to a vehicle condition. In connection with certain specific sensor structures and methods, it has been recognized that such optimal operation can be facilitated by adjusting spring tensions in such a way as to controllably vary certain normally fixed sensor settings. While such approaches are well adapted to the specific sensor structures for which they have been proposed, it is deemed desirable to facilitate optimal response of sensors irrespective of the specific form of sensor employed.